Trudy have you tried installing the Radian rf'ing in your Outlook?
I am wondering if the OP could install the MA ff'ing center & then the RN outboard rf'ing if that would work for her? I know the MA being on a base tend to do better with long belt stalks like the Acadia/Outlook has in the center.
I just can not imagine being in the 3rd row for that long of a trip and also a hassle to get in any out crawling over the kids car seats.
No, I didn't try the radian rf'ing outboard in the 3rd row, but I'd hazard a guess it wouldn't fit in terms of front to back space without having the 2nd row passenger really cramped for room.
The MA installs easily ff'ing in the center of the 3rd row. The shell is narrow enough that it fits right between the contours. I have a pic of the center position:
The Radian just doesn't fit perfectly between those contours. I was able to get the seat rock solid side to side and acceptable front to back (maybe 1/4"?) but was not happy with the amount of the seat that was touching the vehicle seatback... you can't see perfectly in this picture, but it gives you an idea of how the edge of the seat was supported on the one side and behind that was just empty space.
I haven't tried it again since that time, but I just really wasn't happy with the way the seat fit back there - and it seemed to largely be a seat contouring problem. The MA install there was a complete breeze.
I really think ff'ing Radian with the rf'ing MA in the seat directly behind is going to be best bet - though admittedly I never tried to install the MA rf'ing back there.. but I wouldn't anticipate problems from an install point. With one of the captain's chairs able to be flipped forward, it'll be easy to get in the 3rd row, and the 3rd row has decent leg room. If the 2nd row captain chair is moved slightly forward than 2nd and 3rd row leg room should be pretty much equal. I really don't see a rf'ing seat working in the 3rd row without having the 2nd row captain's chair forward - though maybe if that 2nd row is upright that would change things. My 2nd row had been reclined at the time I tried buckling an extra seat in for transport. I don't' remember if it was the snugride or the SS1 now, but I could barely get the carrier snapped on to the base...
eta: Looking through the few pic's I have now I'm doubting a little why I was unhappy with it. I just know my gut instinct was that it wasn't ok there. It's been well over a year since I had it in there though... maybe it's worth another try. If I can convince myself to bring it out of storage in the basement.
eta again.
Here's a pic from the back which gives an idea of how the seat sat in relation to the contours too. So it was over top on one edge and inside on the other. And no amount of trying to change the install is going to fix that.. it's just the width of the radian shell in relation to the contours in the seat. It's possible others would have a different comfort level with it than I did though.